This invention relates to the field of brazing, specifically methods of brazing that are adapted for repeated disassembly and rebrazing cycles.
There are many methods for joining materials, including mechanical fasteners using mechanical interference of the parts, adhesives, welding, and brazing. Some mechanical fasteners used with elastomeric seals can result in a leakproof joint. The joint, however, is often not as strong as the surrounding material or requires significantly increased mass, and is therefore an expected mechanical failure point under high structural or thermal stresses. Welding can also result in a leakproof joint, and a joint that is substantially as strong as the materials. Welded joints must be cut apart for disassembly, making them unsuitable for applications requiring disassembly.
Brazed joints can provide hermetic joints that are substantially as strong as the materials. Additionally, brazed joints can generally be opened by heating the joint enough to remelt the brazing alloy. FIG. 1 (a,b,c) depicts a typical braze joint. In FIG. 1a, components 11, 21 are to be joined at surfaces 1, 2 using braze alloy 3. In FIG. 1b, components 11, 21 have been brought together and heated, melting braze alloy (not shown) and joining surfaces 1, 2 to form joint 4. Conventional component materials and braze alloys result in changed component material properties in the regions 12, 22 near joint 4. FIG. 1c shows components 11, 21 after subsequent heating and disassembly. Surfaces 1, 2 are separated, but the regions 12, 22 of changed component material properties remain. Rebrazing the joint now requires working with the regions 12, 22 of changed component material properties, often degrading the performance of any resulting rebrazed joint or assembly.
Many applications that require the advantages of brazed joints use high value components. Traditional brazing processes limit the number of disassembly/rebrazing cycles before the high value components are unusable. There is a need for a reversible brazing process that allows repeated disassembly and rebrazing cycles.